1. Field of the Invention
The present invention relates to a device that generates highly accurate three-dimensional data at a high speed.
2. Description of the Related Art
In recent years, three-dimensional CG (three-dimensional Computer Graphics) technology has often been used in movies and games. Because three-dimensional CG places and moves three-dimensional models and lighting in a virtual three-dimensional space, a high level of freedom of expression may be obtained.
Non-contact three-dimensional measuring devices using the light-section method and similar methods have conventionally been used commercially. If measurement is performed using such a device, three-dimensional data of the object may be generated.
Furthermore, a stereo imaging device is known that obtains multiple images of an object using two cameras, and that generates three-dimensional data from these images. It comprises multiple cameras in which external parameters (the positions and orientations of the cameras) and internal parameters (the focal lengths, pixel pitch) are calibrated. Mutually corresponding points are sought (this operation is termed ‘searching’ or ‘detection’) regarding the multiple images obtained, and distances are measured based on the principle of triangulation. As a search method for the corresponding points, the correlation method or slope method may be used.
The three-dimensional data generated in the manner described above has a uniform resolution throughout. Therefore, if there is an excessively large amount of data, processing takes a long time, while if there is an excessively small amount of data, poor precision results.
For example, in the case of a stereo imaging device, the distance precision, i.e., the precision regarding the configuration of the object, depends on the accuracy in the search for corresponding points. The precision regarding corresponding points increases as the image resolution increases. However, as the precision or resolution regarding corresponding points increases, the time required for processing also increases. Accordingly, the amount of resulting three-dimensional data also increases.
Normally, an object to be modeled has areas that have complex shape characteristics and areas that do not. For example, in the case of a person's head, the eyes, nose, mouth and ears have complex shape characteristics, but the cheeks and forehead have relatively simple shape characteristics.
Conventionally, where an object to be modeled has both areas with complex shape characteristics and areas with simple shape characteristics, as described above, imaging or measurement is performed using the precision required to perform modeling of a complex configuration, and the amount of the resulting three-dimensional data is reduced by reducing the data in accordance with the three-dimensional characteristics of each area.
However, in the conventional art, because high-precision three-dimensional data is generated first and the data reduction process takes place afterward, the problem arises that the entire processing sequence is time-consuming.